Prevention of ultraviolet-light-induced herpes labialis by sunscreen

Long-term time trends in reactivated herpes simplex infections and treatment in Sweden

Background

Our aim was to describe the annual prevalence of herpes simplex virus (HSV) reactivation in relation to solar ultraviolet (UV) radiation and antiviral drug use in the Swedish adult population.

Methods

The study comprised 2879 anti-HSV-1 immunoglobulin (Ig) G positive subjects from five different cohorts who had donated serum from 1988 to 2010. The sera were analyzed for anti-HSV IgM using enzyme-linked immunosorbent assay. Associations between the presence of anti-HSV IgM antibodies, the apolipoprotein E ε4 allele and the serum sampling year were assessed by logistic regression. Seasonality of anti-HSV IgM was evaluated in a UV radiation model.

Data of antiviral drugs for the entire Swedish population were compiled from two different nationwide databases: the Swedish Prescribed Drug Register and the Swedish Association of the Pharmaceutical Industry.

Results

Cross-sectional and longitudinal analyses indicated that the prevalence of anti-HSV IgM antibodies declined between 1988 and 2010 (odds ratio [OR] = 0.912, p < .001), while the total annual use of antiviral drugs in Sweden gradually increased from 1984 to 2017. Higher UV radiation was associated with higher prevalence of anti-HSV IgM antibodies (OR = 1.071, p = .043).

Conclusion

The declining time trend of HSV reactivation in a Swedish cohort coincides with a steady increase of antiviral drug use in the Swedish general population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07525-w.

Use of Lip Protecting Agents in the Prevention of Actinic Cheilitis, Herpes Labialis and Cancer of Lip: A Systematic Review

Background:

Actinic cheilitis, herpes labialis and lip cancer are relatively common conditions presenting on the lips associated with exposure to periods of sun exposure and thereby ultraviolet radiation.

Objective:

This systematic review aimed to determine the efficacy of the application of sunscreen-containing lip-protecting agents (LPA) in the prevention of actinic cheilitis (AC), recurrent herpes labialis (RHL) and lip cancer (LC).

Methods:

This review was conducted in accordance with the PRISMA guidelines and registered with the PROSPERO database. A literature search was conducted using SCOPUS, Google Scholar, Medline (Ovid), Pubmed, CINAHL, Cochrane Library databases and manual search using search terms actinic cheilitis (AC), recurrent herpes labialis (RHL) and lip cancer (LC) along with lip protecting agents and their variations as keywords. A total of 1,567 papers were yielded. Of them, nine studies were eligible for qualitative data synthesis.

Results:

Nine articles (3 AC, 5 RHL, 1 LC) were deemed eligible and thus selected for qualitative synthesis. Three studies on AC identified approximately 21.7% lower prevalence of lesions when some form of lip protection was used. Eighty percent of studies on RHL identified that the application of LPA is effective in preventing RHL. Subjects who applied LPA more than once daily only had half the risk of having LC compared to those who applied once daily.

Conclusion:

This review of randomised controlled trials (RCTs) and observational studies supports the use of LPA as an effective method in preventing lip-associated lesions. Further, RCTs and observational studies should aim at determining a definitive LPA application regime and optimal SPF strength to prevent lip-associated lesions.

This systematic review was registered with the International Prospective Register of Systematic Reviews (PROSPERO): Registration Number - CRD42020177484. https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020177484

20 years since the Herpetic Eye Disease Study: Lessons, developments and applications to clinical practice

Herpes Simplex Virus (HSV) is the most common virus that causes eye disease. Although around 60% of the world's population are seropositive for HSV antigens, fortunately, it is estimated that only 1% of seropositive individuals develop eye disease. The most common ocular manifestation of HSV is keratitis, while uveitis and retinal necrosis occur in a small number of cases. HSV keratitis is a debilitating disease, for several reasons: pain , photophobia, and vision loss in acute disease, latency of the virus which leads to infection reactivation from various triggers, scarring, and neovascularisation, leading to permanent vision loss with poor visual rehabilitation prospects. The Herpetic Eye Disease Study (HEDS) was a landmark series of randomised controlled trials in the 1990s that set the benchmark for evidence-based treatment guidelines for anterior eye herpetic disease. Since this time, there has been a change in the distribution of seroprevalence of herpes in the community, a simplified diagnostic classification, advances in treatment options, an emergence of new and a better understanding of risk factors, and discoveries in science that show promise for vaccine and novel future treatments. However, many of the principles of the HEDS study remain rightly entrenched in clinical practice. In this article, the HEDS study is revisited 20 years on through the lens of published literature, to determine current best practise and look towards the future.

Solar Ultraviolet Radiation and Vitamin D Deficiency on Epstein-Barr Virus Reactivation: Observational and Genetic Evidence From a Nasopharyngeal Carcinoma-Endemic Population

Background

We investigated the relationship of Epstein-Barr virus viral capsid antigen (EBV VCA-IgA) serostatus with ambient and personal ultraviolet radiation (UVR) and vitamin D exposure.

Methods

Using data from a multicenter case-control study, we included 1026 controls subjects in 2014–2017 in Hong Kong, China. Odds ratios (ORs) and 95% confidence intervals (CIs) of the association between UVR exposure and EBV VCA-IgA (seropositivity vs seronegativity) were calculated using unconditional logistic regression models adjusted for potential confounders.

Results

We observed a large increase in seropositivity of EBV VCA-IgA in association with duration of sunlight exposures at both 10 years before recruitment and age 19–30 years (adjusted OR = 3.59, 95% CI = 1.46–8.77; and adjusted OR = 2.44, 95% CI = 1.04–5.73 for ≥8 vs <2 hours/day; P for trend = .005 and .048, respectively). However, no association of EBV VCA-IgA serostatus with other indicators of UVR exposure was found. In addition, both circulating 25-hydroxyvitamin D (25OHD) and genetic predicted 25OHD were not associated with EBV VCA-IgA serostatus.

Conclusions

Our results suggest that personal UVR exposure may be associated with higher risk of EBV reactivation, but we did not find clear evidence of vitamin D exposure (observational or genetic), a molecular mediator of UVR exposure. Further prospective studies in other populations are needed to confirm this finding and to explore the underlying biological mechanisms. Information on photosensitizing agents, and serological markers of EBV, and biomarkers related to systemic immunity and inflammation should be collected and are also highly relevant in future studies.

A series of in vitro and human studies of a novel lip cream formulation for protecting against environmental triggers of recurrent herpes labialis

Purpose

These studies describe the testing of a novel, daily-use lip cream designed for individuals with lips prone to recurrent herpes labialis (RHL) that protects against environmental triggers.

Subjects and methods

In vitro occlusive and in vitro and in vivo photoprotection analyses, a characterization of normal vs dry lips, and a randomized, evaluator-blinded, clinical trial that assessed the lip cream in healthy subjects with dry lips were conducted. In the clinical trial, subjects applied the lip cream or were untreated and evaluated using transepidermal water loss (TEWL), corneometry, visual assessments of lip dryness, expert photographic evaluations, and subject-rated outcomes.

Results

The lip cream’s in vitro water vapor transmission rate (84.1 g/(m² h)) indicated moderate occlusivity. The lip cream, but not placebo or control (water), reduced ultraviolet A (UVA)- and UVB-induced DNA damage, and tumor necrosis factor-α (EpiDerm^FT) and pros-taglandin E₂ release (EpiDerm^FT and EpiGingival™). The lip cream’s in vivo sun protection factor (SPF) was 12.2 (lower confidence limit, 11.3) and SPF/UVA protection factor ratio was 0.9. The characterization of dry vs normal lips identified differences in moisturization. In the clinical trial, the lip cream significantly decreased TEWL (difference: −7.19 [95% CI: −11.41, −2.98]; P<0.01), increased corneometry (difference: 4.62 [95% CI: 1.05, 8.19]; P<0.05), and reduced visual dryness (difference: −1.48 [95% CI: 2.24, −0.71]; P<0.001) compared to untreated subjects. Significant benefits were also observed on expert photographic assessments of scaling (difference: −0.89 [95% CI: −1.75, −0.03]; P< 0.05), cupping (difference: −1.50 [95% CI: −2.30, −0.70]; P<0.001), and healthy appearance (difference: −1.44 [95% CI: −2.29, −0.58]; P<0.01); differences in overall healthy appearance were not significant (P=0.51). Subject-rated assessments indicated improvements in cracking, dryness, and flaking in the lip cream group but worsening in untreated subjects.

Conclusion

These studies indicate that this novel, daily-use lip cream protects against UV radiation, drying, and chapping, which are established environmental RHL triggers.

Radiation Exposure and Bell's Palsy: A Hypothetical Association

Bell's palsy is an idiopathic peripheral nerve palsy involving the facial nerve. It accounts for 60 to 75% of all cases of unilateral facial paralysis. The main mechanisms to induce BP remain unclear, but infection, ischemic condition and immunodeficiency may contribute to the development of Bell's palsy. Accumulating evidence has shown several factors can trigger the reactivation of latent HSV including psychological stressors, physical stressors and immunosuppression. Ionization and non-ionization radiations are of importance of physical stressors. Some data have shown radiation can reactivate HSVs. Based on preliminary studies showing radiation reactivation of HSVs, we aimed to hypothesize radiation (in both forms of ionization and non-ionization) may cause Bell's palsy. In the future, the role of radiotherapy, radiofrequency radiation from mobile phones and wireless devices in HSV reactivation and Bell's palsy should be investigated.

Cost of Routine Herpes Simplex Virus Infection Visits to U.S. Emergency Departments 2006-2013

Introduction

Little is known about emergency department (ED) utilization for herpes simplex viruses (HSV) types 1 and 2 in the United States. Our goal was to determine the utilization and cost burden associated with HSV infection visits to U.S. EDs in recent years from 2006–2013.

Methods

We analyzed the Nationwide Emergency Department Sample (NEDS) database, the largest national database of hospital-based ED visits in the U.S., to determine the number of visits and the cost associated with HSV visits from 2006–2013. We also analyzed trends across years.

Results

From 2006–2013, there were 704,728 ED visits with a primary diagnosis of HSV infection. Of these, 658,805 (93.5%) resulted in routine discharges without inpatient admission, amounting to a total ED charge of $543.0 million. After adjusting for inflation, there was a doubling of total ED spending for HSV from 2006 to 2013 ($45.0 million to $90.7 million) and a 24% increase in number of visits (73,227 visits in 2006, vs. 90,627 visits in 2013). ED visits for genital herpes have increased while visits for herpes gingivostomatitis have decreased.

Conclusion

HSV-associated ED use and associated costs have increased between 2006–2013. Most of these cases could likely be managed in non-emergent outpatient settings as 93.5% of visits resulted in routine discharges without admission. Our findings add to knowledge regarding HSV utilization and epidemiology in the U.S. and highlight the need for continued prevention, patient education, and emphasis of care in non-emergency settings to prevent unnecessary ED utilization.

Infectious Diseases Associated With Organized Sports and Outbreak Control

Participation in organized sports has a variety of health benefits but also has the potential to expose the athlete to a variety of infectious diseases, some of which may produce outbreaks. Major risk factors for infection include skin-to-skin contact with athletes who have active skin infections, environmental exposures and physical trauma, and sharing of equipment and contact with contaminated fomites. Close contact that is intrinsic to team sports and psychosocial factors associated with adolescence are additional risks. Minimizing risk requires leadership by the organized sports community (including the athlete's primary care provider) and depends on outlining key hygiene behaviors, recognition, diagnosis, and treatment of common sports-related infections, and the implementation of preventive interventions.

HSV-1 clinical isolates with unique in vivo and in vitro phenotypes and insight into genomic differences

Strain-specific factors contribute in significant but undefined ways to the variable incidence of herpes simplex virus (HSV) recrudescence. Studies that investigate these strain-specific factors are needed. Here, we used qPCR, in vitro assays, and genomic sequencing to identify important relationships between in vitro and clinical phenotypes of unique HSV-1 clinical isolates. Nine HSV-1 isolates from individuals displaying varying reactivation patterns were studied. Isolates associated with frequent recurrent herpes labialis (RHL) (1) displayed higher rates of viral shedding in the oral cavity than those associated with rare RHL and (2) tended to replicate more efficiently at 33 °C than 39 °C. HSV-1 isolates also displayed a more stable phenotype during propagation in U2OS cells than in Vero cells. Draft genome sequences of four isolates and one variant spanning 95.6 to 97.2 % of the genome were achieved, and whole-genome alignment demonstrated that the majority of these isolates clustered with known North American/European isolates. These findings revealed procedures that could help identify unique genotypes and phenotypes associated with HSV-1 isolates, which can be important for determining viral factors critical for regulating HSV-1 reactivation.

Progress in the Clinical Management of Herpesvirus Infections

Antiviral drug discovery has produced a series of drugs active against herpesviruses in vitro. Several of these are now licensed and/or have been used in clinical practice. This article reviews the mechanisms of action of acyclovir, ganciclovir, penciclovir, sorivudine and foscarnet, the development of resistance to these drugs and their pharmacokinetic and cellular toxicities. Based upon the natural histories of HSV, VZV and CMV, treatment objectives for each virus are discussed and the performance of each drug matched against these objectives. Overall, it is concluded that the perfect drug for treating herpesviruses does not exist, but that significant progress has been made towards controlling several herpesvirus diseases. It is suggested that further progress will require not just improved drug discovery programmes, but also an understanding of different pathogeneses and an appreciation by practising physicians that antiviral drugs must be given early in the infectious process to achieve the best results.

Current strategies for prevention of oral manifestations of human immunodeficiency virus

OBJECTIVES

Strategies to prevent new-onset and recurrent oral manifestations of human immunodeficiency virus (HIV), including fungal, viral, neoplastic, and idiopathic mucosal diseases and destructive periodontal conditions, are poorly understood.

STUDY DESIGN

A structured review of the English language literature in PubMed through March 2015 was conducted to identify current prevention strategies for initial and recurrent oral manifestations of HIV.

RESULTS

Pharmacologic approaches, including combination antiretroviral therapy or other targeted therapies for prevention of oropharyngeal candidiasis, orolabial herpes, oral hairy leukoplakia, oral Kaposi sarcoma, linear gingival erythema and necrotizing ulcerative periodontitis were found. Nonpharmacologic approaches for prevention of oropharyngeal candidiasis, orolabial herpes, oral hairy leukoplakia, and necrotizing ulcerative periodontitis are presented.

CONCLUSIONS

Current strategies for the prevention of oral manifestations of HIV include pharmacologic and nonpharmacologic therapies. Immune reconstitution inflammatory syndrome, future vaccine therapy for pathogens causing oral mucosal disease, and the possible role of oral inflammatory disease prevention in controlling HIV disease progression are discussed.

Role of activating transcription factor 3 in the synthesis of latency-associated transcript and maintenance of herpes simplex virus 1 in latent state in ganglia

A key property of herpes simplex viruses (HSVs) is their ability to establish latent infection in sensory or autonomic ganglia and to reactivate on physical, hormonal, or emotional stress. In latently infected ganglia, HSVs express a long noncoding RNA, a latency-associated transcript (LAT), which plays a key role in maintaining latently infected neurons, but not viral proteins. To investigate the events leading to reactivation, we examined the use of ganglionic organ cultures that enable rapid reactivation in medium containing antibody to nerve growth factor (NGF) or delayed reactivation in medium containing NGF and epidermal growth factor (EGF). Here we report the discovery that activating transcription factor 3 (ATF3), a stress response protein, profoundly affects the interaction of HSV with its host. Specifically, (i) ATF3 is induced by stress, such as inhibition of protein synthesis or infection; (ii) in infected cells, ATF3 enhances the accumulation of LAT by acting on the response elements in the promoter of the LAT precursor RNA; (iii) ATF3 is induced nearly 100-fold in ganglionic organ cultures; and (iv) ATF3 plays a key role in the maintenance of the latent state, inasmuch as expression of ATF3 bereft of the C-terminal activation domain acts as a dominant negative factor, inducing HSV gene expression in ganglionic organ cultures harboring latent virus and incubated in medium containing NGF and EGF. Thus, ATF3 is a component of a cluster of cellular proteins that together with LAT maintain the integrity of the neurons harboring latent virus.

Interventions for prevention of herpes simplex labialis (cold sores on the lips)

BACKGROUND

Herpes simplex labialis (HSL), also known as cold sores, is a common disease of the lips caused by the herpes simplex virus, which is found throughout the world. It presents as a painful vesicular eruption, forming unsightly crusts, which cause cosmetic disfigurement and psychosocial distress. There is no cure available, and it recurs periodically.

OBJECTIVES

To assess the effects of interventions for the prevention of HSL in people of all ages.

SEARCH METHODS

We searched the following databases up to 19 May 2015: the Cochrane Skin Group Specialised Register, the Oral Health Group Specialised Register, CENTRAL in the Cochrane Library (Issue 4, 2015), MEDLINE (from 1946), EMBASE (from 1974), LILACS (from 1982), the China National Knowledge Infrastructure (CNKI) database, Airiti Library, and 5 trial registers. To identify further references to relevant randomised controlled trials, we scanned the bibliographies of included studies and published reviews, and we also contacted the original researchers of our included studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of interventions for preventing HSL in immunocompetent people.

DATA COLLECTION AND ANALYSIS

Two authors independently selected trials, extracted data, and assessed the risk of bias. A third author was available for resolving differences of opinion.

MAIN RESULTS

This review included 32 RCTs, with a total of 2640 immunocompetent participants, covering 19 treatments. The quality of the body of evidence was low to moderate for most outcomes, but was very low for a few outcomes. Our primary outcomes were 'Incidence of HSL' and 'Adverse effects during use of the preventative intervention'.The evidence for short-term (≤ 1 month) use of oral aciclovir in preventing recurrent HSL was inconsistent across the doses used in the studies: 2 RCTs showed low quality evidence for a reduced recurrence of HSL with aciclovir 400 mg twice daily (risk ratio (RR) 0.26, 95% confidence interval (CI) 0.13 to 0.51; n = 177), while 1 RCT testing aciclovir 800 mg twice daily and 2 RCTs testing 200 mg 5 times daily found no similar preventive effects (RR 1.08, 95% CI 0.62 to 1.87; n = 237; moderate quality evidence and RR 0.46, 95% CI 0.20 to 1.07; n = 66; low quality evidence, respectively). The direction of intervention effect was unrelated to the risk of bias. The evidence from 1 RCT for the effect of short-term use of valaciclovir in reducing recurrence of HSL by clinical evaluation was uncertain (RR 0.55, 95% CI 0.23 to 1.28; n = 125; moderate quality evidence), as was the evidence from 1 RCT testing short-term use of famciclovir.Long-term (> 1 month) use of oral antiviral agents reduced the recurrence of HSL. There was low quality evidence from 1 RCT that long-term use of oral aciclovir reduced clinical recurrences (1.80 versus 0.85 episodes per participant per a 4-month period, P = 0.009) and virological recurrence (1.40 versus 0.40 episodes per participant per a 4-month period, P = 0.003). One RCT found long-term use of valaciclovir effective in reducing the incidence of HSL (with a decrease of 0.09 episodes per participant per month; n = 95). One RCT found that a long-term suppressive regimen of valaciclovir had a lower incidence of HSL than an episodic regimen of valciclovir (difference in means (MD) -0.10 episodes per participant per month, 95% CI -0.16 to -0.05; n = 120).These trials found no increase in adverse events associated with the use of oral antiviral agents (moderate quality evidence).There was no evidence to show that short-term use of topical antiviral agents prevented recurrent HSL. There was moderate quality evidence from 2 RCTs that topical aciclovir 5% cream probably has little effect on preventing recurrence of HSL (pooled RR 0.91, 95% CI 0.48 to 1.72; n = 271). There was moderate quality evidence from a single RCT that topical foscarnet 3% cream has little effect in preventing HSL (RR 1.08, 95% CI 0.82 to 1.40; n = 295).The efficacy of long-term use of topical aciclovir cream was uncertain. One RCT found significantly fewer research-diagnosed recurrences of HSL when on aciclovir cream treatment than on placebo (P < 0.05), but found no significant differences in the mean number of participant-reported recurrences between the 2 groups (P ≥ 0.05). One RCT found no preventive effect of topical application of 1,5-pentanediol gel for 26 weeks (P > 0.05). Another RCT found that the group who used 2-hydroxypropyl-β-cyclo dextrin 20% gel for 6 months had significantly more recurrences than the placebo group (P = 0.003).These studies found no increase in adverse events related to the use of topical antiviral agents.Two RCTs found that the application of sunscreen significantly prevented recurrent HSL induced by experimental ultraviolet light (pooled RR 0.07, 95% CI 0.01 to 0.33; n = 111), but another RCT found that sunscreen did not prevent HSL induced by sunlight (RR 1.13, 95% CI 0.25 to 5.06; n = 51). These RCTs did not report adverse events.There were very few data suggesting that thymopentin, low-level laser therapy, and hypnotherapy are effective in preventing recurrent HSL, with one to two RCTs for each intervention. We failed to find any evidence of efficacy for lysine, LongoVital® supplementation, gamma globulin, herpes simplex virus (HSV) type I subunit vaccine, and yellow fever vaccine in preventing HSL. There were no consistent data supporting the efficacy of levamisole and interferon, which were also associated with an increased risk of adverse effects such as fever.

AUTHORS' CONCLUSIONS

The current evidence demonstrates that long-term use of oral antiviral agents can prevent HSL, but the clinical benefit is small. We did not find evidence of an increased risk of adverse events. On the other hand, the evidence on topical antiviral agents and other interventions either showed no efficacy or could not confirm their efficacy in preventing HSL.

Effectiveness of topical corticosteroids in addition to antiviral therapy in the management of recurrent herpes labialis: a systematic review and meta-analysis

BACKGROUND

Recurrent herpes labialis (RHL) is one of the most common viral infections worldwide. The available treatments have limited efficacy in preventing the recurrence of ulcerative lesions and reducing the duration of illness. The objective of this review was to identify the effectiveness of topical corticosteroids in addition to antiviral therapy in the treatment of RHL infection.

METHODS

A systematic review of randomized clinical trials comparing the efficacy of combined therapy (topical corticosteroids with antiviral) with placebo or antiviral alone in the management of RHL was conducted. MEDLINE, EMBASE, CINAHL, Web of Science, the Cochrane library, and Google Scholar databases were searched. We used RevMan software to conduct the meta-analysis. A fixed-effects model was used for mild to moderate heterogeneity, whereas a random-effects model was used for significant heterogeneity. Heterogeneity among trials was established using I(2) and chi-square test for heterogeneity.

RESULTS

Four studies that fulfilled the selection criteria were included in this review. The total number of participants across included studies was 1,891 (range, 29 to 1,443). The antiviral drugs used were acyclovir, famciclovir, and valacyclovir. Corticosteroids used were 1% hydrocortisone and 0.05% fluocinonide. Pooled results showed that patients receiving combined therapy had a significantly lower recurrence rate of ulcerative lesions compared to those in both the placebo group (OR, 0.50; 95% CI, 0.39-0.66; P < .001) and the antiviral treatment alone group (OR, 0.73, 95% CI, 0.58-0.92; P = .007). The healing time was also significantly shorter in combined therapy in comparison to placebo (P < .001). However, there were no significant differences in healing time between combined therapy and antiviral alone. The adverse reactions in combined therapy were not significantly different than the placebo group (OR, 1.09; 95% C, 0.75-1.59; P = .85).

CONCLUSION

Treatment with combined therapy is safe and more effective than placebo or antiviral alone for preventing the recurrence of ulcerative lesions in RHL infection.

Association between unprotected ultraviolet radiation exposure and recurrence of ocular herpes simplex virus

Studies have suggested that exposure to ultraviolet (UV) light may increase risk of herpes simplex virus (HSV) recurrence. Between 1993 and 1997, the Herpetic Eye Disease Study (HEDS) randomized 703 participants with ocular HSV to receipt of acyclovir or placebo for prevention of ocular HSV recurrence. Of these, 308 HEDS participants (48% female and 85% white; median age, 49 years) were included in a nested study of exposures thought to cause recurrence and were followed for up to 15 months. We matched weekly UV index values from the National Oceanic and Atmospheric Administration to each participant's study center and used marginal structural Cox models to account for time-varying psychological stress and contact lens use and selection bias from dropout. There were 44 recurrences of ocular HSV, yielding an incidence of 4.3 events per 1,000 person-weeks. Weighted hazard ratios comparing persons with ≥8 hours of time outdoors to those with less exposure were 0.84 (95% confidence interval (CI): 0.27, 2.63) and 3.10 (95% CI: 1.14, 8.48) for weeks with a UV index of <4 and ≥4, respectively (ratio of hazard ratios = 3.68, 95% CI: 0.43, 31.4). Though results were imprecise, when the UV index was higher (i.e., ≥4), spending 8 or more hours per week outdoors was associated with increased risk of ocular HSV recurrence.

The consequences of UV-induced immunosuppression for human health

Exposure to UV radiation can cause suppression of specific immune responses. The pathways leading to the down-regulation are complex, starting from the absorption of UV photons by chromophores in the skin and ending with local and systemic changes in immune mediators, the generation of T and B regulatory cells and inhibition of effector and memory T cell activation. The consequences for human health are thought to be both beneficial and adverse. The former are illustrated by protection against polymorphic light eruption, and possible protection against T cell-mediated autoimmune diseases and asthma. The latter are illustrated by skin cancer, cutaneous lupus erythematosus and infectious diseases including vaccination. Many outstanding questions remain in this rapidly developing and controversial area, not least what advice to give the general public regarding their sun exposure. While considerable advances have been made in the development of strategies that preserve the health benefits of sunlight exposure and decrease its detrimental effects, further research is required before optimal levels of protection are achieved.

Delaying the expression of herpes simplex virus type 1 glycoprotein B (gB) to a true late gene alters neurovirulence and inhibits the gB-CD8+ T-cell response in the trigeminal ganglion

Following herpes simplex virus type 1 (HSV-1) ocular infection of C57BL/6 mice, activated CD8(+) T cells specific for an immunodominant epitope on HSV-1 glycoprotein B (gB-CD8 cells) establish a stable memory population in HSV-1 latently infected trigeminal ganglia (TG), whereas non-HSV-specific CD8(+) T cells are lost over time. The retention and activation of gB-CD8 cells appear to be influenced by persistent viral antigenic exposure within the latently infected TG. We hypothesized that the low-level expression of gB from its native promoter before viral DNA synthesis is critical for the retention and activation of gB-CD8 cells in the TG during HSV-1 latency and for their ability to block HSV-1 reactivation from latency. To test this, we created a recombinant HSV-1 in which gB is expressed only after viral DNA synthesis from the true late gC promoter (gCp-gB). Despite minor growth differences compared to its rescuant in infected corneas, gCp-gB was significantly growth impaired in the TG and produced a reduced latent genome load. The gCp-gB- and rescuant-infected mice mounted similar gB-CD8 effector responses, but the size and activation phenotypes of the memory gB-CD8 cells were diminished in gCp-gB latently infected TG, suggesting that the stimulation of gB-CD8 cells requires gB expression before viral DNA synthesis. Surprisingly, late gB expression did not compromise the capacity of gB-CD8 cells to inhibit HSV-1 reactivation from latency in ex vivo TG cultures, suggesting that gB-CD8 cells can block HSV-1 reactivation at a very late stage in the viral life cycle. These data have implications for designing better immunogens for vaccines to prevent HSV-1 reactivation.

Topical n-docosanol for management of recurrent herpes labialis

IMPORTANCE OF THE FIELD

Recurrent herpes labialis (RHL) is a significant disorder with social and health consequences that affects upwards of 20 - 40% of the adult population. Docosanol is the only FDA-approved topical agent that is available over the counter for management of RHL. Its mechanism of action is unique compared with other available antiviral agents.

AREAS COVERED IN THIS REVIEW

The authors conducted a comprehensive search of the published preclinical and clinical literature on topical docosanol for RHL. All of the published literature relating to docosanol and its use for the management of recurrent herpes labialis was reviewed, from the first report of docosanol to 31 January 2010.

WHAT THE READER WILL GAIN

The objective of this review was to summarize and critically evaluate the available literature with respect to topical docosanol's mechanism, safety and efficacy in the management of RHL.

TAKE HOME MESSAGE

Ten percent docosanol cream is a safe and effective topical treatment for the management of RHL in immunocompetent adults, with essentially equivalent efficacy compared with other available prescription topical antiviral agents. Owing to its unique mechanism of action, there is little to no risk of developing resistance.

Alternative therapies for common dermatologic disorders, part 1

The exact pathophysiology and curative treatment of many common dermatologic conditions remain unclear. Often conventional treatments are only partially effective, leading patients to look for alternative treatments. Rosacea may be helped by azelaic acid. Seborrheic dermatitis may be helped by tea tree oil. Chronic urticaria may be helped by a focused dietary history and elimination of food additives and salicylates. Although various alternative treatments have been touted as useful in herpes simplex, few have proved efficacious.

CD8 T cell control of HSV reactivation from latency is abrogated by viral inhibition of MHC class I

In humans, herpes simplex virus (HSV) establishes latency in sensory nerve ganglia from where it periodically reactivates, whereas in murine models, the virus efficiently establishes latency but rarely reactivates. HSV inhibits MHC class I antigen presentation to CD8 T cells efficiently in humans but poorly in mice, and whether this is a crucial determinant of HSV's ability to reactivate in humans remains uncertain. To test this, we generated a panel of recombinant HSVs that inhibit presentation by murine MHC class I mimicking the effect in humans. Antigen-specific CD8 T cells prevent the in vivo reactivation of wild-type HSV. Despite their presence in the ganglia of latently infected mice, CD8 T cells do not prevent the reactivation of recombinant HSVs that inhibit murine MHC class I in mice. These findings suggest that efficient inhibition of MHC class I by HSV is a key factor in its ability to reactivate in humans.

Human herpes simplex virus infections: epidemiology, pathogenesis, symptomatology, diagnosis, and management

Eight of the more than 80 known herpesviruses are human pathogens. Human herpes simplex virus (HSV) is a contagious infection with a large reservoir in the general population. It has a potential for significant complications in the immunocompromised host. In addition, psychological distress caused by the negative stigma associated with genital herpes and visible facial lesions in those experiencing frequent outbreaks renders it a challenging clinical dilemma. This article reviews the epidemiology, pathogenesis, and diagnostic features of HSV infections, providing the clinician with an up-to-date understanding of the available management strategies for mucocutaneous HSV-induced disease.

Variation in the WBC differential count and other factors associated with reporting of herpes labialis: A population-based study of adults

Reactivation of latent herpes virus has been linked to triggers of mild immunosupression, such as stress or UV-exposure. Despite having predictive value in severe immunodeficiency, the white blood cell (WBC) differential count has not been examined in relation to risk of herpes reactivation in population studies. The WBC differential count and other risk factors for herpes labialis were examined in 5687 adults (ages 18-64) from the Third National Health and Nutrition Examination Survey, who had WBC 3.5-11 x 10(6) cells mL(-1) and reported no acute infections in the past month. The association between self-reported herpes labialis in the past year and the WBC differential count was modeled, adjusting for age, sex, race/ethnicity, education, smoking, upper respiratory infections (URI), and HSV-1 antibodies. Herpes labialis was significantly associated with white race/ethnicity, being a nonsmoker, and frequent URI. Compared with the highest quartile, being in the lowest quartile of granulocytes was associated with herpes labialis, adjusted odds ratio=1.82 (95% confidence interval 1.20, 2.28). At the same time, there was a trend towards an inverse association of lower lymphocyte count and herpes labialis. These findings suggest that moderate differences in the WBC differential count are related to reactivation of HSV-1. Prospective studies may help to show whether such differences indicate susceptibility to loss of latency or represent a consequence of reactivated infection.

Management of recurrent oral herpes simplex infections

The literature has been reviewed for evidence of the efficacy of antiviral agents in both the prophylaxis and treatment of recurrent oral herpes simplex virus (HSV) infections and discussed by a panel of experts. Emphasis was given to randomized controlled trials. Management of herpes-associated erythema multiforme and Bell palsy were also considered. The evidence suggests that 5% acyclovir (ACV) in the cream base may reduce the duration of lesions if applied early. Recurrent herpes labialis (RHL) and recurrent intraoral HSV infections can be effectively treated with systemic ACV 400 mg 3 times a day or systemic valacyclovir 500 to 1000 mg twice a day for 3 to 5 days (longer in the immunocompromised). RHL in the immunocompetent can be effectively prevented with (1) sunscreen alone (SPF 15 or above), (2) systemic ACV 400 mg 2 to 3 times a day, or (3) systemic valacyclovir 500 to 2000 mg twice a day. Valacyclovir 500 mg twice a day is also effective in suppressing erythema multiforme triggered by HSV. Further studies are needed to compare treatment efficacy between topical penciclovir, docosanol, and ACV cream for RHL.

Management of oral lesions in HIV-positive patients

HIV/AIDS is currently the leading cause of death in Africa and the fourth leading cause of death worldwide. This systematic review of the literature was conducted to evaluate the evidence for treatment of the most common oral lesions associated with HIV: oral candidiasis with or without oropharyngeal involvement (OPC), oral hairy leukoplakia (OHL), recurrent aphthous-like ulcerations (RAU), oral Kaposi's sarcoma (OKS), orolabial herpes simplex infection (HSV), oral herpes zoster infection (VZV), intraoral or perioral warts (HPV), and HIV-associated periodontal diseases. Treatment of HIV-associated salivary gland disease is addressed in a different section of this World Workshop. We found the largest body of evidence for treatment of OPC in HIV patients. Future trials will be needed to test drugs currently in development for treatment of Candida strains that are resistant to existing therapies. There were no double blind, placebo-controlled randomized clinical trials (RCT) for topical treatment of OHL, and only one RCT for systemic treatment of the lesion with desciclovir. Systemic thalidomide was the only drug tested in RCT for treatment or prevention of RAU. Only 1 double-blind RCT comparing vinblastine and sodium tetradecyl sulfate was identified for localized treatment of OKS. Three drugs (famciclovir, acyclovir, and valaciclovir) were shown to be effective in randomized, double-blind trials for treatment or suppression of mucocutaneous HSV lesions in HIV patients. In all 3 trials, the effects of these medications on orolabial HSV lesions were not reported separately. There were no double-blind, placebo-controlled RCT testing topical treatments for orolabial HSV lesions in HIV patients. No trials testing treatments of oral VZV were identified. There were no double-blind, placebo-controlled RCT for treatment of HIV-associated intraoral or perioral warts or periodontal diseases. In conclusion, there is a need for well-designed RCTs to assess the safety and efficacy of topical and systemic treatments of most oral mucosal and perioral lesions in HIV patients. There is also a need to develop newer drugs for treatment of resistant fungal and viral microorganisms. Finally, standardized outcome measures should be developed for future clinical trials to allow comparisons of studies using different populations.

Perineal herpes simplex infection in bedridden geriatric patients

BACKGROUND

Herpes simplex virus (HSV) lesions are prone to reactivation and recurrence in response to various local or systemic triggering factors.

OBJECTIVE

To study the characteristics of five bedridden geriatric patients who presented with herpetic recurrences on the buttocks, gluteal cleft, and perianal region during hospitalization.

METHODS

Data were gathered regarding age, gender, reason for hospitalization, localization of lesions, clinical presentation, previous clinical diagnosis and topical treatments, immune status and immunosuppressant drug intake, as well as prior history of labial or genital herpes. A skin biopsy was taken for histologic examination and immunohistochemical viral identification. Viral culture and viral serology were performed and data regarding antiviral therapy were recorded.

RESULTS

The five patients (three women, two men) were aged >80 years and hospitalized for either severe drug-induced renal insufficiency (one case), severe pneumonia (two cases), or stroke causing restricted mobility (two cases). Numerous well demarcated, painful ulcerations developed in the perianal region of these patients, and one patient also presented with some vesicular lesions. The lesions had been confused with mycotic and/or bacterial infections for 10-14 days. No inguinal lymphadenopathies were present and there was no fever. None of the patients had a previous history of recurrent labial or genital HSV infections or HIV infection. Histology was suggestive of HSV infection in two of five patients. Immunohistochemistry identified HSV type I (three patients) and HSV type II (two patients) infections. Viral culture with immunofluorescence viral identification revealed HSV type I in one of the four patients in whom a swab for viral culture was taken. Serology revealed past HSV infection. All lesions cured gradually after 10-14 days of intravenous acyclovir (aciclovir) treatment.

CONCLUSION

Herpetic lesions of the perineal region represent a rare complication in bedridden geriatric patients in the absence of a previous history of HSV infections at the same site. Common traits of patients with this condition were the presence of numerous ulcerated lesions, prolonged time course, and confinement to bed. The latter probably modifies the skin condition, which triggers viral reactivation and favors cutaneous extension of the infection. Complementary diagnostic methods for viral detection and identification are mandatory.

Oral and perioral herpes simplex virus type 1 (HSV-1) infection: review of its management

Herpes simplex virus type 1 (HSV-1) gives rise to a variety of clinical disorders and is a major cause of morbidity and mortality worldwide. HSV-1 infections are common in oral and perioral area. The aim of the present report was to critically examine the published literature to evaluate the advantages and limitations of therapy of HSV-1 infection in both immunocompetent and immunocompromised patients. Systemic antiviral therapy has been widely accepted as effective for primary herpetic gingivostomatitis. Aciclovir (ACV) 5% cream seems to be the accepted standard topical therapy for herpes labialis, being both effective and well tolerated, although penciclovir 1% cream has been proposed as a potentially useful treatment. Systemic ACV may be effective in reducing the duration of symptoms of recurrent HSV-1 infection, but the optimal timing and dose of the treatment are uncertain. Aciclovir and famciclovir may be of benefit in the acute treatment of severe HSV-1 disease in immunocompromised patients. There is also evidence that prophylactic oral ACV may reduce the frequency and severity of recurrent attack of herpetic infection in immunocompromised patients, but the optimal timing and duration of treatment is uncertain and can vary in different situations.

The Effect of Ultraviolet Radiation on Human Viral Infections

Exposure to UV radiation is recognized to suppress cell-mediated immunity and therefore could adversely affect the course of a viral infection. Rodent models of viral infection confirm this possibility but the situation in human subjects is not so clear, apart from two exceptions. These are herpes simplex, in which sunlight exposure can cause reactivation, and certain papillomavirus types in which sunlight exposure can lead to the development of nonmelanoma skin cancer. In both cases, there are UV response elements in the viral genomes that alter the normal interactions between the viruses and the host following exposure, and UV-induced effects on the immune response occur in addition. These complex mechanisms are discussed, and the situation regarding UV radiation and viral exanthems plus other viruses, including the retroviruses, summarized. Finally viral vaccination is considered in the context of UV exposure and the importance of the host's genetic background emphasized. Further research is required to evaluate whether sunlight can significantly affect the resistance to common viral infections and vaccines.

Ultraviolet protective performance of photoprotective lipsticks: change of spectral transmittance because of ultraviolet exposure

BACKGROUND

Photoinstability of sunscreens because of ultraviolet (UV) exposure is a well-known and common phenomenon. Recently, it was also shown that sunscreens with complex filter combinations are photoinactivated by UV exposures, which can easily be acquired by solar exposure over several hours.

OBJECTIVES

To assess the change of the spectral transmission after UV exposure (UV-challenged protective performance) of 27 commercially available photoprotective lipsticks.

METHODS

Quartz slides were covered with a lipstick layer (area density 1.0+/-0.1 mg/cm2) and irradiated with increasing doses of solar-simulated radiation. The spectral transmission (T) was measured spectrophotometrically before and after 5, 12.5, 25, and 50 standard erythema doses (SED) of exposure. We calculated the change in transmission (photoinstability) as the difference between the spectral transmission before and after a defined UV exposure, DeltaT, and the arithmetic mean, for both the UVA (DeltaTA) and UVB (DeltaTB) ranges. A product was labelled as photounstable if the mean photoinstability in the UVA, DeltaTA, or UVB range, DeltaTB, was higher than 5% for an UV exposure of 12.5 SED.

RESULTS

Eleven products showed a significant photoinstability in the UVA range (DeltaTA between 6% and 27%), only one product in the UVB range (DeltaTB = 13%), and one product in both the UVA (DeltaTA = 31%) and UVB (DeltaTB = 9%) range. In one product photoinstability became significant in the UVA range at higher UV exposures.

CONCLUSIONS

Out of 27 lipsticks only 13 products showed a photostable performance (DeltaTA < 5% and DeltaTB < 5% for 12.5 SED). We propose therefore that only products, which fulfil these UV photostability criteria should be marketed.

Skin infections and ageing

Elderly individuals have an increased susceptibility to skin infections due to age-related anatomical, physiological and environmental factors. The types of organisms that cause primary skin and soft tissue infections are diverse, and include bacterial, viral and fungal pathogens as well as parasites. In the elderly, these infections and infestations may present with atypical signs and symptoms or may complicate underlying chronic skin disorders. Clinical features, investigations and management of the following important and common skin infections are described in more detail: cellulitis, erysipelas, necrotizing fasciitis, impetigo, folliculitis, furunculosis and carbunculosis, erythrasma, herpes zoster and postherpetic neuralgia, herpes simplex, warts, molluscum contagiosum, dermatophytosis of the skin, hair and nails, candidiasis, and scabies. Treatment should be based on the results of the appropriate diagnostic tests. Correct diagnosis and therapy of skin infections lead to satisfactory outcome in the majority of elderly patients.

Topical and systemic photoprotection

Sunscreens are a valuable method of sun protection. Several new compounds are now available. It is important to remember, however, that photoprotection includes more than the use of sunscreens. There are a number of sun-protective behaviors that people can use to decrease their exposure to ultraviolet (UV) radiation. Dermatologists and other health professionals can work toward changing public policy, greatly increasing the ability of people to access shade. In addition, there is growing evidence about the effectiveness of other sun-protective agents. The only systemic medication for sun protection is beta-carotene, which is effective in erythropoietic protoporphyria (EPP).

Assessment of thickness of photoprotective lipsticks and frequency of reapplication: results from a laboratory test and a field experiment

BACKGROUND

The thickness of the sunscreen layer that is actually applied by consumers under usual conditions has been determined for photoprotective lotions and creams; however, this question is still unanswered for photoprotective lipsticks.

OBJECTIVES

To assess lipstick thickness (area density) and frequency of application per day for two commercially available photoprotective lipsticks with different consistency.

METHODS

The study consisted of a laboratory test and a field experiment. In the laboratory test the applied lipstick thickness was determined as area density in mg cm(-2) for a group of 28 panellists under standardized conditions. In a separate group of 18 subjects we assessed the area density and the frequency of application per day for two photoprotective lipsticks during a 6-day skiing course.

RESULTS

In the laboratory test the median and 95% confidence interval of the area density was 0.98 mg cm(-2) (0.66-1.65) and 0.86 mg cm(-2) (0.63-1.40) for products A and B, respectively. The respective values of the field experiment were 1.58 mg cm(-2) (0.79-2.23) (product A) and 1.76 mg cm(-2) (1.16-3.50) (product B). Only 11% of all applications of lipstick A and 6% of all applications of lipstick B reached the reference area density of 2.0 mg cm(-2). The difference between the median of the area density for lipstick A (firm consistency) and lipstick B (soft consistency) was not statistically significant. No statistically significant influence on the area density was found for age, sex, photobiological skin type or regular lipstick use. The median daily frequency of application was 2.2 times for lipstick A and 3.0 times for lipstick B.

CONCLUSION

Our investigation shows that photoprotective lipsticks are applied in a much thinner layer than recommended by international standards (2 mg cm(-2)). This results in a significant reduction of the photoprotective capacity. Furthermore, the frequency of application is too low for adequate protection. Therefore, we propose that the sun protection factor (SPF) should be assessed for an area density that reflects the actual usage patterns. As long as the test protocol is not adapted to the reduced area density, photoprotective lipsticks with high and ultrahigh SPF should be recommended, especially for individuals with increased risk for the development of lip malignancies.

Viral diseases of the oral mucosa

A wide variety of both DNA and RNA viruses affect the oral cavity. When considered in conjunction with cutaneous features, careful examination of the oral mucosa and oropharynx aids the clinician in making a diagnosis. Examination of the oral cavity should be incorporated as a regular component of the dermatologic examination because diagnostic clues are readily available to assist in the evaluation of infectious processes.

Health effects from stratospheric ozone depletion and interactions with climate change

The potential health effects of elevated levels of ambient UV-B radiation are diverse, and it is difficult to quantify the risks, especially as they are likely to be considerably modified by human behaviour. Nevertheless epidemiological and experimental studies have confirmed that UV radiation is a definite risk factor for certain types of cataract, with peak efficacy in the UV-B waveband. The causal link between squamous cell carcinoma and cumulative solar UV exposure has been well established. New findings regarding the genetic basis of skin cancer, including studies on genetically modified mice, have confirmed the epidemiological evidence that UV radiation contributes to the formation of basal cell carcinomas and cutaneous melanomas, For the latter, animal models have demonstrated that UV exposure at a very young age is more detrimental than exposure in adulthood. Although suppression of certain immune responses has been recognised following UV exposure, the impact of this suppression on the control of infectious and autoimmune diseases is largely unknown. However, studies on several microbial infections have indicated significant consequences in terms of symptoms or reactivation of disease. The possibility that the immune response to vaccination could be depressed by UV-B exposure is of considerable concern. Newly emerging possibilities regarding interactions between ozone depletion and global climate change further complicate the risk assessments for human health but might result in an increased incidence of cataracts and skin cancer, plus alterations in the patterns of certain categories of infectious and other diseases.

Treatment of mucocutaneous presentations of herpes simplex virus infections

Infections by herpes simplex virus (HSV) types I and II are diverse and quite frequent. After primary infection, the virus establishes a life-long latency in the sensory ganglia and recrudescences may occur at an unpredictable rate. Recurrent labial and genital herpes infections represent the majority of clinical manifestations of HSV infections. Their management is currently well established using evidence-based medicine data. Primary labial herpes is generally not treated with antivirals in otherwise healthy children, although intravenous aciclovir may be offered in severe primary infections, particularly in the immunocompromised patient. The decision whether or not to treat recurrent labial herpes should be evaluated individually and depends on the frequency and severity of relapses, the impairment of the quality of life, and the cost of therapy. Patients with mild disease may benefit from topical therapy, and those with severe and frequent recurrences may be considered for intermittent or long-term oral antiviral therapy. Primary genital herpes is treated with oral or intravenous antivirals, depending on the severity of the infection and associated symptoms. Recurrent genital herpes can be managed with episodic short courses of oral antivirals in patients whose recurrences are moderate to severe and rare, and have a clear prodrome. Patients with >5 episodes/year, severe recurrences or unrecognisable prodromes may be best managed with long-term suppressive antiviral prophylaxis. HSV is also responsible for a variety of other clinical manifestations, including herpetic whitlow, neonatal infection, disseminated and atypical cutaneous infections, traumatic herpes, eczema herpeticum, and HSV-associated erythema multiforme. HSV infection may also represent a complication following cosmetic procedures of the oro-facial region, surgical and dental interventions, sun exposure and burns. Precise treatment guidelines for these HSV infections are not firmly established.

The effect of sunscreen on melanoma risk

The usage of sunscreens has grown dramatically worldwide over the past decade. Current data suggest that a regimen of sun protection that includes protective clothing, avoiding midday sun, and regular use of broad-spectrum high SPF sunscreen (such as practiced in Australia [19]) seems to be reducing melanoma incidence rates. This is the current recommendation of the American Academy of Dermatology and it is also the recommendation that is best supported by existing data. Except for total sun avoidance, sunscreens remain the best individual method of protection from UV-induced damage to the skin. It is hoped there will be even more definitive answers to questions related to the effectiveness of sunscreens for reducing melanoma risk as better sunscreen components are developed and as evaluations are performed in the future that overcome the problems better in existing studies.

Amsterdam Cohort Study on HIV and AIDS: impact of exposure to UVR as estimated by means of a 2-year retrospective questionnaire on immune parameters in HIV positive males

We studied a group of HIV-infected homosexuals who participated in the Amsterdam Cohort Study on HIV and AIDS to investigate whether greater exposure to sunlight is associated with a less favorable course of some important immunological parameters. This was done because ultraviolet radiation (UVR) is potentially harmful to the cellular immunity and may enhance viral replication. The exposure to UVR was estimated by means of a 2-year retrospective questionnaire in 1997. Both a 2-year cumulative estimate and estimates by 3-monthly episodes were calculated. The associations with CD4+ T-cell count, CD4+/CD8+ T-cell ratio, and T-cell reactivity were investigated. First, the associations between the cumulative estimate and the individual slopes of these parameters during the 2 years covered by the questionnaire were explored by means of a robust regression analysis. Secondly, the short-term association with the estimate by episode was examined by means of a linear mixed-effect model for repeated measurements (LME). No statistically significant associations with the cumulative estimate were found. Although a trend to lower values of the immunological parameters studied after short-term greater exposure in the LME model was observed, the differences were not statistically significant either. These findings suggest that exposure to sunlight does not have a suppressive effect on the above mentioned immunological parameters in HIV-infected persons.

Seasonal influences on immunological parameters in HIV-infected homosexual men: searching for the immunomodulating effects of sunlight

In view of the capacity of ultraviolet radiation (UVR) to induce suppression of various immunological parameters and to enhance the viral replication of HIV, we investigated whether seasonal influences on immunological parameters that are relevant for HIV infection could be identified. As the sunny season is associated with high levels of ambient UVR, a decline of immunological parameters and an increase of the HIV viral load during the summer months might ensue. We analysed the immunological data of the HIV-infected homosexual men who participated in the Amsterdam Cohort Study on HIV infection and AIDS (1984-1996; n = 556). The effect of season on the individual development of various immunological parameters in time was examined by means of a random effects model for repeated measurements. Lower levels in the mean number of CD4+ T cells and the mean CD4+/CD8+ ratio were found during summer and spring, respectively (P = 0.0001/0.0001). For the CD8+ T cells, high mean values were observed both in April and September (P = 0.0001). The highest T-cell reactivity values were found during the summer (P = 0.0001). No effect of season on the viral load was established. The seasonal effect on CD4+ T cells seemed to be more pronounced at a more advanced stage of the HIV infection. It is concluded that the lower CD4+ T-cell counts during summer support the notion that solar UVR may have a suppressive effect on the cellular immunity of HIV-infected persons. However, whether this observation can be attributed to the effect of ambient UVR solely is questionable, as the other immunological parameters follow different seasonal courses and other reports suggest that both internal and environmental factors influence immunological parameters.

The roles of inflammation, STAT transcription factors, and nerve growth factor in viral reactivation and herpes keratitis

Nerve growth factor (NGF) has an inhibitory effect while inflammatory cytokines may stimulate herpes simplex virus (HSV) reactivation. NGF binds to its receptor trkA on terminal axons and signals the neuron cell body in the ganglion. Many cytokines may also signal neurons through their specific receptors, affecting STAT transcription factors within the cell bodies. We studied the effects of trigeminal ganglion (TG) explantation, a powerful HSV reactivation stimulus, on the NGF/trkA and the JAK/STAT signaling pathways. Immunohistochemistry and gel shifting experiments were performed using anti-STAT, anti-trkA, or negative control antibodies on mouse TGs. The expression of neuronal trkA was greatly reduced or eliminated by 3 days postexplantation. In contrast, the expression of STAT1, STAT3, and STAT5b, as well as phosphotyrosine-STAT3 were relatively preserved in these explanted TGs. Gel-shifting experiments indicated that TG nuclear extracts bind specifically to the HSV-1 LAT promoter, an important viral gene that regulates reactivation. STAT1, but not STAT3 or STAT5b, was detected as a component of this LAT binding complex. These studies suggest that the inhibitory effects of NGF/trkA signaling are lost after TG explantation while STAT expression is maintained, allowing HSV-1 reactivation to proceed.

A review of studies on the effects of ultraviolet irradiation on the resistance to infections: evidence from rodent infection models and verification by experimental and observational human studies

Recent studies on the immunosuppressive effects of ultraviolet radiation (UVR) and the related resistance to infections in rodents and humans are presented. The waveband dependency of trans-to-cis isomerisation of urocanic acid in the stratum corneum and the role of DNA damage in UVR-induced erythema and immunosuppression were investigated to further elucidate the underlying mechanisms. Furthermore, human experimental studies on UVR-induced immunomodulation were performed. It appeared that the doses needed to suppress various immune parameters in humans (e.g. NK activity, contact hypersensitivity) were higher than those needed in experiments in rodents. Still, extrapolation of experimental animal data to the human situation showed that UVR may impair the resistance to different systemic infections at relevant outdoor doses. In observational human studies we aimed to substantiate the relevance of UVR for infections in humans. It was shown that sunny season was associated with a slightly retarded but clinically non-relevant antibody response to hepatitis B vaccination. Furthermore, sunny season appeared to be associated with a small decline in the number of CD4+ T-helper cells in a cohort of HIV-infected persons and a higher recurrence of herpes simplex and herpes zoster in a cohort of renal transplant recipients. However, in a study among young children a higher exposure to solar UVR was associated with a lower occurrence of upper respiratory tract symptoms. As disentangling the effects of UVR from other relevant factors is often impossible in observational studies, concise quantitative risk estimations for the human situation cannot be given at present.

Ultraviolet light induced injury: immunological and inflammatory effects

This article reviews many of the complex events that occur after cutaneous ultraviolet (UV) exposure. The inflammatory changes of acute exposure of the skin include erythema (sunburn), the production of inflammatory mediators, alteration of vascular responses and an inflammatory cell infiltrate. Damage to proteins and DNA accumulates within skin cells and characteristic morphological changes occur in keratinocytes and other skin cells. When a cell becomes damaged irreparably by UV exposure, cell death follows via apoptotic mechanisms. Alterations in cutaneous and systemic immunity occur as a result of the UV-induced inflammation and damage, including changes in the production of cytokines by keratinocytes and other skin-associated cells, alteration of adhesion molecule expression and the loss of APC function within the skin. These changes lead to the generation of suppressor T cells, the induction of antigen-specific immunosuppression and a lowering of cell-mediated immunity. These events impair the immune system's capacity to reject highly antigenic skin cancers. This review gives an overview of the acute inflammatory and immunological events associated with cutaneous UV exposure, which are important to consider before dealing with the complex interactions that occur with chronic UV exposure, leading to photocarcinogenesis.

Effects of solar radiation on the human immune system

On UV irradiation of the skin, a complex cascade of immunological changes results, initiated by cutaneous chromophores and ending in suppression of some local and systemic immune responses. In this review, the stages in this process are outlined first, concentrating on the roles of DNA and urocanic acid as photoreceptors. Evidence indicating UV-induced immunomodulation of delayed hypersensitivity and resistance to infectious diseases in human subjects follows. Aspects of genetic susceptibility to the immunosuppressive effects of UV exposure and extrapolation of the data obtained in animal models to the human situation are included. Finally uncertain and unknown factors relating to the impact of UV on the human immune system are discussed.